MuseLegal locks every matter down to its assigned people

MuseLegal's change introduces an explicit roster for each matter: clients, attorneys, reviewers and paralegals are listed against the matters they're actually assigned to, and partners and admins get the keys to everything. Documents, portal messages, tasks, intake submissions and downloadable files all inherit the same rule - if you're not on the matter, you don't see it.

The part worth noting is that the check runs twice: once in the application and once in the database itself, so a slip in the app layer still gets caught underneath. It's freshly merged and the team flags a few loose ends - some configuration isn't bundled in, it sits alongside the original sharing logic, and no tests shipped with it - so treat it as a strong skeleton rather than a finished feature.